<?php
	class A{
//		const C='A';
//		const D='C';
		public static $c='A';
		public static $d='C';
		public function m(){
			echo static::$c;
		}
		public function n(){
			echo self::$d;
		}
	}
	class B extends A{
//		const C="B";
//		const D="D";
		public static  $c='B';
		public static  $d='D';
	}
	$b=new B();
	$b->m();
	$b->n();
